The invention relates to the handling of elongate articles, preferably fuel elements. The fuel elements, together with their control elements, are disposed so as to be directly adjacent to one another, in a so-called narrow position, in the pressurized water reactor core of a nuclear power station. When stored, the fuel elements are mounted at a distance from one another, in a so-called wide position, in a fuel element storage rack in the fuel element storage pool of the nuclear power station. In the case of a change of fuel element, spent fuel elements have to be transported out of the reactor core into the storage rack and fresh fuel elements have to be transported out of the storage pool into the reactor core. The invention relates, in general terms, to a loading machines or more specifically a refueling machine, for handling elongate articles, the longitudinal axis of which is oriented in a geodetically vertical direction. A plurality of these articles is disposed so as to be directly adjacent to one another in a so-called near position and so as to be at a slight distance from one another in a so-called wide position. The loading machine serves, in particular, for transporting such articles out of a closely packed bundle of these articles to a workplace or set-down location or storage location. Conversely, the loading machine also serves for combining such set-down articles to form a closely packed bundle.
The preferred use of the invention for the handling of fuel elements and control rods in a nuclear power plant is primarily described below, although this does not rule out other ways of using the invention.
In nuclear power stations with light water reactors, the reactor core is accommodated in the reactor pressure vessel. In this case, the reactor core has a plurality of fuel elements which are of essentially elongate parallelepipedal shape and are oriented geodetically vertical so as to be closely adjacent to one another. In order to control the nuclear reaction, a plurality of these fuel elements have control rods which are introduced into the fuel elements through guide tubes contained in fuel elements.
During the operating period of a nuclear reactor, the nuclear fuel contained in the fuel elements is consumed by being burnt up, with the result that the fuel elements have to be exchanged from time to time. Since the burn-up of fuel elements depends on their position in the reactor core, the fuel elements are not consumed simultaneously. Fuel elements not burnt up completely are usually transferred in the reactor core. The exchange and transfer of fuel elements takes place after an operating cycle of the power plant of several (for example, 12 or 18) months.
To change a fuel element, the reactor has to be shut down and made pressureless. By demounting the pressure vessel cover and removing various internal fittings, the reactor core becomes accessible from above. This is carried out, with the reactor pool flooded, in order to obtain water shielding for the exposed reactor core. A manipulating bridge, together with a gripper suspended in a guide mast, can then be moved over the flooded fuel element storage pool and the reactor space. Each position in the storage rack and reactor core can be approached with the aid of a positioning system, that is adjusted or calibrated according to coordinates.
In order to handle fuel elements and control rods and also throttle devices, which close off the control rod guide tubes of those fuel elements having no control rods, it is possible, for example, to use a so-called double gripper, such as is described in Published German Patent Application DE 17 64 176. This double gripper is vertically movable and is equipped with a control rod gripper and a fuel element gripper, each of which can be operated independently. The double gripper is provided within a guide mast fastened to the manipulating bridge. Disposed within the guide mast is a centering bell surrounding the double gripper. This device is telescopic, in such a way that the centering bell can be moved out of the guide mast. The centering bell centers the double gripper above the fuel element to be gripped, specifically by coupling to fuel element centering devices, which are adjacent to the fuel element to be gripped. The double gripper is moved out of the centering bell in order to grip a fuel element or its control rods. After the double gripper has gripped a fuel element or its control rods, the double gripper, together with the gripped fuel element or the gripped control rods, is moved into the centering bell, and the latter, in turn, is moved into the guide mast. The fuel element can then, through the use of the manipulating bridge, be transferred in the reactor core or delivered to a fuel element storage rack. Conversely, a fuel element can be gripped from a fuel element storage rack and delivered to the reactor core.
The duration of the exchange of a fuel element constitutes a substantial cost factor since the nuclear power station is shut down during this time. moreover, during the change of a fuel element, the operation personnel is exposed to radiation.
It is accordingly an object of the invention to provide a loading machine for transferring elongate articles, such as fuel elements, and a corresponding method for transferring fuel elements which overcome the above-mentioned disadvantages of the heretofore-known machines and methods of this general type and which shorten the time necessary for changing the fuel element.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method for simultaneously transferring two fuel elements in a nuclear power station, the method includes the steps of:
providing a loading machine having a mast divided into two mast parts provided parallel to one another and movable horizontally relative to one another, and the loading machine having respective grippers and lifting devices for raising and lowering two fuel elements in the two mast parts;
positioning the loading machine over a reactor core or a storage rack of a nuclear power station; gripping each of the two fuel elements and lifting each of the two fuel elements into a corresponding one of the mast parts;
positioning the loading machine, together with the two fuel elements lifted into the two mast parts, over the storage rack or the reactor core in the nuclear power station;
changing a mutual spacing distance between the two fuel elements by moving the two mast parts relative to one another; and
lowering the two fuel elements out of the mast parts and into the storage rack or the reactor core.
In other words, the method according to the invention makes it possible to transfer fuel elements, for example between the reactor core (narrow fuel element spacing) and the fuel element storage rack, a workplace for inspection or another set-down location (widened fuel element spacing, possibly a changed orientation). In this case, a plurality of fuel elements, which are disposed or are to be disposed next to one another in the reactor core, are simultaneously or successively lifted out of their initial position and drawn into a hollow mast which is formed of a plurality of parts movable relative to one another. Each fuel element is guided and held on its own part of the mast. Subsequently, the parts of the mast, together with the fuel elements held in them, are transported jointly to a location in the power station at which they are lowered out of the parts of the mast and set down in a final or ultimate position. The mast parts (including the fuel element in each case held on them) are displaced relative to one another and rotated about a longitudinal direction of the corresponding mast part before or after transport, in such a way that the fuel elements acquire the same spacing and the same orientation relative to one another as are desired for their ultimate position.
The orientation of at least one fuel element in the initial position may be different from that in the ultimate or final position and the fuel element must therefore be rotated. In this case, preferably, the mast part carrying this element is, before or after transport, moved away from the other mast parts in the horizontal direction, is rotated and subsequently brought closer to them again. This temporary removal or moving away is necessary due to space restrictions. Neither the fuel elements nor the mast parts, together with the machine parts provided on them, must be damaged during rotation.
In accordance with another mode of the invention, the two mast parts are moved between a first end position and a second end position by moving the two mast parts relative to one another.
A hollow mast is formed with the two mast parts, the hollow mast being open at a bottom and being essentially closed in a lateral direction when the two mast parts are in the first end position. A hollow mast is also formed with the two mast parts, the hollow mast being open at the bottom and being divided laterally into two halves by longitudinal gaps of a given width when the two mast parts are in the second end position. The two mast parts are brought in the first end position when the loading machine is positioned above the reactor core and the two mast parts are brought in the second end position when the loading machine is positioned above the storage rack.
In accordance with a further mode of the invention, the two mast parts are brought in the first end position after the two fuel elements are lifted into the hollow mast. Subsequently, the loading machine is moved between the reactor core and the storage rack.
In view of the object of the invention, there is also provided, in combination with a nuclear power station having a reactor core and fuel elements, a loading machine for transferring the fuel elements in the nuclear power station, the loading machine including:
a trolley movable in a horizontal plane in the nuclear power station between a point above the reactor core and a further point above a set-down location;
a hollow mast held by the trolley, the hollow mast having an open end pointing downward from the trolley;
gripping devices, guiding devices and holding devices movable together with the hollow mast for gripping the fuel elements individually, moving the fuel elements up and down in the hollow mast and, at the same time, guiding and holding the fuel elements inside the hollow mast;
the hollow mast having an inner cross section adapted to a cross section formed by two of the fuel elements closely adjacent to one another, corresponding to a position of the fuel elements in the reactor core, the hollow mast being divided into two mast parts, the two fuel elements being received simultaneously in the hollow mast;
the gripping devices, the guiding devices and the holding devices each being assigned to a respective one of the two fuel elements for gripping, holding, moving up and down and guiding the two fuel elements independently of one another; and
the two mast parts being movable on the trolley in a horizontal direction relative to one another, each respective one of the two mast parts being movable together with respective ones of the gripping devices, the guiding devices and the holding devices assigned the respective one of the two fuel elements.
In other words, a suitable device is based on a hollow mast which, pointing downward and open at the bottom, is held on a trolley which is movable in a horizontal plane in the power station between a point above the reactor core and a point above a set-down location or storage location. Provided on the mast are gripping, guiding and holding devices, which are movable together with the mast, grip the fuel element, can move up and down and, at the same time, guide and hold the fuel element.
According to the invention, the inner cross section of the mast is adapted to the cross section of two fuel elements disposed next to one another. The inner cross section is adapted in such a way that the two fuel elements are simultaneously accommodated inside the mast and are independently movable up and down by gripping, guiding and holding devices, which are mounted there and are in each case assigned to an individual fuel element. The mast and these devices are divided into two halves assigned in each case to a fuel element, these halves being held on the trolley in such a way that they are movable relative to one another in the horizontal direction. Preferably, at least one half of the mast is rotatable about a longitudinal axis.
The object of the invention applies not only to fuel elements but also to the control elements of the reactor or to similar articles. The object is achieved with a loading machine that includes:
a lifting device for raising and lowering two elongate articles selectively simultaneously and independently of one another, the two elongate articles each having a longitudinal axis oriented geodetically vertically;
a moving device for equidirectionally moving the two elongate articles in a geodetically longitudinal direction and a geodetically transverse direction;
a rotating device for rotating the two elongate articles about one of a common horizontal axis and independent horizontal axes through at least 90xc2x0 in a first direction of rotation and through at least 180xc2x0 in a second direction of rotation opposite the first direction of rotation; and
a further moving device for moving the two elongate articles relative to one another in a geodetically horizontal direction.
In other words, according to the invention, a loading machine is provided for the simultaneous handling of two elongate articles, the longitudinal axis of which is oriented geodetically vertically. This loading machine has a device for the simultaneous raising or lowering of these articles. However, the same device also allows the articles to be raised or lowered independently of one another. Furthermore, the loading machine has a device for the equidirectional movement of these articles in the geodetic longitudinal and transverse directions. The loading machine has, moreover, a device for rotating these articles about a common axis through at least 90xc2x0 in one direction of rotation and through at least 180xc2x0 in the opposite direction of rotation. Furthermore, the loading machine has one or two devices for the nonequidirectional geodetically horizontal movement of at least one of these articles and also one or two devices for rotating these articles independently of one another in each case about different axes in each case through at least 90xc2x0 in one direction of rotation and through at least 180xc2x0 in the opposite direction of rotation. The devices for the nonequidirectional movement of the handled articles therefore allow a movement of these articles relative to one another.
In accordance with another feature of the invention, the lifting device handles the two elongate articles selectively in a narrow position with the two elongate articles positioned directly adjacent to one another and in a wide position with the two elongate articles spaced apart from one another by a given distance.
In accordance with yet another feature of the invention, a geodetically vertically oriented guide mast with a geodetically vertically oriented centering bell is provided. The centering bell can be drawn into the guide mast and moved out of the guide mast. A double gripper is movable into and out of the centering bell, the double gripper having a first, outer gripper and a second, inner gripper provided concentrically in the outer gripper. The guide mast is divided in two guide mast parts in a vertical direction and the centering bell is divided in two centering bell parts in the vertical direction. A further gripper is at least partially essentially structurally identical to the double gripper.
In accordance with another feature of the invention, the loading machine includes axially mounted rotary shields, each of the guide mast parts, a respectively associated one the centering bell parts and a respectively associated one of the double gripper and the further gripper are provided on a respective one of the axially mounted rotary shields.
In accordance with a further feature of the invention, the two elongate articles have respective vertical mid-axes, the rotary shields are respectively rotatable about the vertical mid-axes.
With the objects of the invention in view there is also provided, a method of moving fuel elements and control elements in a nuclear power station, the method including the steps of:
providing a lifting device for raising and lowering elongate articles selectively simultaneously and independently of one another, the elongate articles each having a longitudinal axis oriented geodetically vertically;
providing a moving device for equidirectionally moving the elongate articles in a geodetically longitudinal direction and a geodetically transverse direction;
providing a rotating device for rotating the elongate articles about one of a common horizontal axis and independent horizontal axes through at least 90xc2x0 in a first direction of rotation and through at least 180xc2x0 in a second direction of rotation opposite the first direction of rotation;
providing a further moving device for moving the elongate articles relative to one another in a geodetically horizontal direction;
providing at least one of fuel elements and control rods as the elongate articles; and
selectively performing at least one of the steps of at least partially filling a reactor core with at least one of the fuel elements and the control rods, at least partially emptying the reactor core, and changing a position of the at least one of the fuel elements and the control rods in the reactor core.
With the objects of the invention in view there is further provided, a method of moving fuel elements and control elements in a nuclear power station, which includes the steps of:
providing a lifting device for raising and lowering at least one of fuel elements and control rods selectively simultaneously and independently of one another, the at least one of the fuel elements and control rods each having a longitudinal axis oriented geodetically vertically;
providing a geodetically vertically oriented guide mast with a geodetically vertically oriented centering bell, the centering bell configured for being drawn into the guide mast and being moved out of the guide mast;
providing a double gripper movable into and out of the centering bell, the double gripper having a first, outer gripper and a second, inner gripper provided concentrically in the outer gripper;
configuring the outer gripper for gripping the fuel elements and configuring the inner gripper for gripping the control rods;
providing the guide mast as being divided in two guide mast parts in a vertical direction and providing the centering bell as being divided in two centering bell parts in the vertical direction; and
providing a further gripper at least partially essentially structurally identical to the double gripper, and configuring the further gripper at least for gripping the fuel elements;
providing a moving device for equidirectionally moving the fuel elements and the control rods in a geodetically longitudinal direction and a geodetically transverse direction; and
selectively performing at least one of the steps of at least partially filling a reactor core with at least one of the fuel elements and the control rods, at least partially emptying the reactor core, and changing a position of at least one of the fuel elements and the control rods in the reactor core.
With the objects of the invention in view there is also provided, a loading machine, including:
a lifting device for raising and lowering a first number of elongate articles selectively simultaneously and independently of one another, the first number being larger than two, each of the elongate articles having a longitudinal axis oriented geodetically vertically;
a moving device for equidirectionally moving the first number of elongate articles in a geodetically longitudinal direction and a geodetically transverse direction;
a rotating device for rotating the first number of elongate articles about independent horizontal axes through at least 90xc2x0 in a first direction of rotation and through at least 180xc2x0 in a second direction of rotation opposite the first direction of rotation; and
a second number of further moving devices for moving the first number of elongate articles relative to one another in at least one of the geodetically longitudinal direction and the geodetically transverse direction, the second number corresponding to the first number.
In other words, the invention also provides a loading machine for the simultaneous handling of three or more elongate articles, the longitudinal axis of which is oriented geodetically vertically. This loading machine, too, has a device for the simultaneous raising or lowering of these articles, which also makes it possible to raise or lower these articles independently of one another. This loading machine also has a device for the equidirectional movement of these articles in the geodetic longitudinal and transverse directions and also a device for rotating these articles about a common axis through at least 90xc2x0 in one direction of rotation and through at least 180xc2x0 in the opposite direction of rotation. Furthermore, the loading machine for the simultaneous handling of three or more of the articles has a number, corresponding to the number of simultaneously handleable articles, of devices for the movement of the handled articles relative to one another in the geodetic longitudinal and/or transverse direction. It has, furthermore, a number, corresponding to the number of simultaneously handleable articles, of devices for rotating the handled articles independently of one another in each case about different axes in each case through at least 90xc2x0 in one direction of rotation and through at least 180xc2x0 in the opposite direction of rotation.
In accordance with another feature of the invention, the lifting device handles the first number of elongate articles selectively in a narrow position with the first number of elongate articles positioned directly adjacent to one another and in a wide position with the first number of elongate articles spaced apart from one another by a given distance.
Since two or more of the elongate articles can be handled simultaneously through the use of the loading appliance, the result of this is, advantageously, that the time required for handling the articles is shortened considerably. However, the loading machine also makes it possible to handle fewer articles than corresponds to the capacity of the loading machine. Furthermore, it makes it possible to handle the individual articles independently of one another to the necessary extent. Thus, for example, the positions of the articles relative to one another can be varied, so that they can be changed over from a mutually narrower configuration into a mutually wider configuration. It is also possible for the articles to be rotated independently of one another about one axis.
The loading machine, through the use of which two of the articles can be handled simultaneously, has, advantageously, a geodetically vertically oriented guide mast, a geodetically vertically oriented centering bell, which can be drawn into the guide mast and can be moved out of the latter, and also a double gripper, which can be moved into and out of this centering bell, with a first, outer gripper and a second, inner gripper disposed concentrically in the outer gripper. At the same time, the guide mast and the centering bell are divided in two in the vertical direction. In the guide bell there is a further gripper which has, at least partially, elements essentially structurally identical to those of the double gripper.
Also, similar to the preferred embodiment of the loading machine for the simultaneous handling of two of the articles, there is a preferred embodiment of the loading machine for the simultaneous handling of three or more of the articles. In this embodiment, the guide mast and the centering bell are divided in the vertical direction according to the number of simultaneously handleable articles. Furthermore, there is a number of grippers corresponding to the number, less one, of the simultaneously handleable articles. The grippers have, at least partially, elements essentially structurally identical to those of the double gripper.
With these preferred embodiments, it is possible to grip the articles, which are to be handled, in a spatially accurate manner by the respective grippers, since the grippers are centered, via the centering bell, relative to the articles to be handled. Since the grippers move the articles to be handled into the centering bell and the centering bell in turn can be moved into the guide mast, a corresponding protection of the handled articles is ensured. In order to allow a relative movement of the individual articles to be handled, the centering bell and the guide mast are divided in their vertical direction.
In a particularly advantageous embodiment of the above loading machines, at least a number, corresponding to the number, less one, of the simultaneously handled articles, of parts of the guide mast and of the respectively associated part of the centering bell, as well as the respectively associated gripper, are provided in each case on an axially mounted rotary shield.
In a particularly advantageous embodiment, each of the rotary shields is rotatable about the vertical mid-axis of the article handleable through the use of the respectively associated gripper. This allows that the article to be handled can be to be rotated about its own axis, without thereby varying the position of the article to be rotated in relation to the other articles handled simultaneously with it.
Advantageously, loading machines of the type described above are used for the at least partial filling and/or emptying of reactor cores with fuel elements or for changing the position of fuel elements and/or control rods in a reactor core.
When loading machines of the type described above are used for changing fuel elements and control rods in a nuclear reactor, the outer gripper of the double gripper is advantageously configured for gripping fuel elements and the inner gripper of the double gripper is advantageously configured for gripping control rods. The other grippers present are configured at least in such a way that fuel elements can be gripped by them.
With the objects of the invention in view there is also provided, a method of moving fuel elements and control elements in a nuclear power station, which includes the steps of:
providing a lifting device for raising and lowering a first number of elongate articles selectively simultaneously and independently of one another, the first number being larger than two, each of the elongate articles having a longitudinal axis oriented geodetically vertically;
providing a moving device for equidirectionally moving the first number of elongate articles in a geodetically longitudinal direction and a geodetically transverse direction;
providing a rotating device for rotating the first number of elongate articles about independent horizontal axes through at least 90xc2x0 in a first direction of rotation and through at least 180xc2x0 in a second direction of rotation opposite the first direction of rotation; and
providing a second number of further moving devices for moving the first number of elongate articles relative to one another in at least one of the geodetically longitudinal direction and the geodetically transverse direction, the second number corresponding to the first number;
providing at least one of fuel elements and control rods as the elongate articles; and
selectively performing at least one of the steps of at least partially filling a reactor core with at least one of the fuel elements and the control rods, at least partially emptying the reactor core, and changing a position of least one of the fuel elements and the control rods in the reactor core.
With the objects of the invention in view there is further provided, an a method of moving fuel elements and control elements in a nuclear power station, which includes:
providing a lifting device for raising and lowering a first number of elongate articles selectively simultaneously and independently of one another, the first number being larger than two, each of the elongate articles having a longitudinal axis oriented geodetically vertically;
providing a geodetically vertically oriented guide mast with a geodetically vertically oriented centering bell, the centering bell configured for being drawn into the guide mast and being moved out of the guide mast;
providing a double gripper movable into and out of the centering bell, the double gripper having an outer gripper and an inner gripper provided concentrically in the outer gripper;
providing a second number of grippers at least partially essentially structurally identical to the double gripper, the second number corresponding to the first number less one;
providing the guide mast as being divided in a vertical direction into a third number of guide mast parts, the third number corresponding to the first number, and providing the centering bell as being divided in the vertical direction into a fourth number of centering bell parts, the fourth number corresponding to the first number;
providing a moving device for equidirectionally moving the first number of elongate articles in a geodetically longitudinal direction and a geodetically transverse direction;
providing a rotating device for rotating the first number of elongate articles about independent horizontal axes through at least 90xc2x0 in a first direction of rotation and through at least 180xc2x0 in a second direction of rotation opposite the first direction of rotation;
providing at least one of fuel elements and control rods as the elongate articles;
configuring the outer gripper for gripping the fuel elements and configuring the inner gripper for gripping the control rods; and selectively performing at least one of the steps of at least partially filling a reactor core with at least one of the fuel elements and the control rods, at least partially emptying the reactor core, and changing a position of at least one of the fuel elements and the control rods in the reactor core.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method for simultaneously transferring fuel elements and as embodied in a loading machine for transferring closely adjacent elongate articles, in particular fuel elements, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.